Gypsum panels, systems, and methods

ABSTRACT

Gypsum panels and methods of making the same are provided. A method of making a gypsum panel includes forming a first gypsum slurry by combining stucco, water, a siliconate, and a phosphate salt or polymer, and setting the first gypsum slurry to form at least part of a core of the gypsum panel, wherein the gypsum panel displays a 2-hour water absorption test weight increase of at least 10 weight percent less than an otherwise identical comparative panel containing no phosphate salt or polymer in its core.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of Ser. No. 16/536,607filed on Aug. 9, 2019 which claims priority to U.S. ProvisionalApplication No. 62/728,095, filed on Sep. 7, 2018, the disclosures ofwhich are incorporated by reference herein in their entireties.

BACKGROUND

The present invention relates generally to the field of panels for usein building construction, and more particularly to gypsum panels andmethods of making gypsum panels.

Typical building panels, such as building sheathing or roof panels,include a core material, such as gypsum, and a mat facer, such as afiberglass mat facer. During manufacturing, the gypsum core material istraditionally applied as a slurry to a surface of the mat facer andallowed to set, such that the mat facer and gypsum core are adhered atthe interface. Often, such panels suffer from water intrusion and otherperformance issues.

Accordingly, it would be desirable to provide panels having improvedwater-resistive properties.

SUMMARY

Gypsum panels and methods of making gypsum panels are provided. A methodof making a gypsum panel includes: forming a first gypsum slurry bycombining stucco, water, a siliconate, and a phosphate salt or polymer;and setting the first gypsum slurry to form at least part of a core ofthe gypsum panel, wherein the gypsum panel displays a 2-hour waterabsorption test weight increase of at least 10 weight percent less thanan otherwise identical comparative panel containing no phosphate salt orpolymer in its core.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, which are meant to be exemplary and notlimiting, and wherein like elements are numbered alike. The detaileddescription is set forth with reference to the accompanying drawingsillustrating examples of the disclosure, in which use of the samereference numerals indicates similar or identical items. Certainembodiments of the present disclosure may include elements, components,and/or configurations other than those illustrated in the drawings, andsome of the elements, components, and/or configurations illustrated inthe drawings may not be present in certain embodiments.

FIG. 1 is a cross-sectional view of a gypsum panel.

FIG. 2 is a cross-sectional view of a gypsum panel

FIG. 3 is a perspective view of a building sheathing system.

FIG. 4 is a graph showing the total water absorption weight difference(%) for various samples as tested in the Examples.

FIG. 5 is a graph showing the total water absorption weight difference(%) for various samples as tested in the Examples.

FIG. 6 is a graph showing the total water absorption weight difference(%) for various samples as tested in the Examples.

FIG. 7 is a graph showing the total water absorption weight difference(%) for various samples as tested in the Examples.

FIG. 8 is a graph showing the total water absorption weight difference(%) for various samples as tested in the Examples.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Improved water repelling, or water-resistive, gypsum panels have beendeveloped, along with associated methods for their manufacture. Incertain embodiments, the panels contain a relatively high amount of asiliconate in at least a portion (e.g., in at least a layer) of thegypsum panel core, optionally without any siloxane. In certainembodiments, the relatively high amount of siliconate is combined with arelatively low amount of siloxane. Further, the siliconate and/or blendof siliconate/siloxane is combined with a phosphate salt or polymer.Such panels have been discovered to display improved water-resistant andmoisture migration properties, while maintaining the mechanicalproperties of gypsum products, such as nail pull and flexural strength,compressive strength and humid bond.

Generally, this disclosure is intended to encompass various forms ofgypsum panel products, such as sheathing panels, roofing panels, andother glass mat and paper faced gypsum panels. While certain embodimentsmay be described with reference to the term “sheathing” or “roofing”, itshould be understood that the panels described herein are not meant tobe limited to these particular uses, and that the features of panelsdescribed as sheathing or roofing panels may be encompassed by othertypes of gypsum panels.

As used herein, the term “water-resistive” or similar phrases refers tothe ability of a panel or system to resist liquid or bulk water frompenetrating, leaking, or seeping past the sheathing and into thesurrounding wall components. Such properties may be further definedaccording to various ASTM test methods, which are described herein.

Gypsum panels or boards may contain a set gypsum core sandwiched betweentwo mats, one or both of which may be coated. The mat coating may be asubstantially continuous barrier coating. As used herein, the term“substantially continuous barrier coating” refers to a coating materialthat is substantially uninterrupted over the surface of the mat.

During manufacturing, a gypsum slurry may be deposited on the uncoatedsurface of a facer material, such as a paper sheet or fiberglass mat(which may be pre-coated offline or online), and set to form a gypsumcore of the panel. The gypsum slurry may penetrate some portion of thethickness of the fiberglass mat or adhere to a paper facing material,and provide a mechanical bond for the panel. The gypsum slurry may beprovided in one or more layers, having the same or differentcompositions, including one or more slate coat layers. As used herein,the term “slate coat” refers to a gypsum slurry having a higher wetdensity than the remainder of the gypsum slurry that forms the gypsumcore.

While this disclosure is generally directed to gypsum panels, it shouldbe understood that other cementitious panel core materials are alsointended to fall within the scope of the present disclosure. Forexample, cementitious panel core materials such as those includingmagnesium oxide or aluminosilicate may be substituted for the gypsum ofthe embodiments disclosed herein, to achieve similar results.

Moreover, while embodiments of the present disclosure are describedgenerally with reference to fiberglass mats or paper facing materials,it should be understood that other mat materials, including otherfibrous mat materials, may also be used in the present panels. Incertain embodiments, the nonwoven fibrous mat is formed of fibermaterial that is capable of forming a strong bond with the material ofthe building panel core through a mechanical-like interlocking betweenthe interstices of the fibrous mat and portions of the core material.Examples of fiber materials for use in the nonwoven mats includemineral-type materials such as glass fibers, synthetic resin fibers, andmixtures or blends thereof. Both chopped strands and continuous strandsmay be used.

Various embodiments of this disclosure are for purposes of illustrationonly. Parameters of different steps, components, and features of theembodiments are described separately, but may be combined consistentlywith this description of claims, to enable other embodiments as well tobe understood by those skilled in the art. Various terms used herein arelikewise defined in the description, which follows.

Methods

In certain embodiments, methods of making gypsum panels in accordancewith this disclosure include forming a first gypsum slurry by combiningstucco, water, a siliconate, and a phosphate salt or polymer, andsetting the first gypsum slurry to form at least part of a core of thegypsum panel. The siliconate may be present in the slurry in an amountthat is higher than is typical, such as from about 3 lb/msf to about 50lb/msf, for a gypsum panel having a thickness of about ¼ inch to about 1inch. As used herein the term “about” is used to refer to is used torefer to plus or minus 2 percent of the relevant numeral that itdescribes. These methods may be used to produce gypsum panels having anyof the features, or combinations of features, described herein. Inparticular, these methods may be used to produce gypsum panels thatdisplays a 2-hour water absorption test weight increase of at least 10weight percent less than an otherwise identical comparative panelcontaining no phosphate salt or polymer in its core. For example, thesemethods may be used to produce gypsum panels having improvedwater-resistant characteristics, such as gypsum panels that display awater absorption of less than about 15 percent, such as 5 percent, byweight, after a 2-hour immersion.

The panel thickness ranges given herein are meant to be exemplary, andit should be understood that panels in accordance with the presentdisclosure may have any suitable thickness. Where amounts of materialspresent within the panel are defined in terms of lb/msf over a certainthickness of panel, it should be understood that the amount of therelevant material described to be present per volume of the panel may beapplied to various other panel thicknesses. In certain embodiments, thepanels have a thickness from about ¼ inch to about 1 inch. For example,the panels may have a thickness of from about ½ inch to about ⅝ inch,such as from about ½ inch to about %, as generally described.

In some embodiments, the first gypsum slurry contains siliconate but isfree of siloxane, while achieving the water-resistant propertiesdescribed herein. In other embodiments, the first gypsum slurry containsstucco, water, a siloxane, and a siliconate. In such embodiments, theratio of siloxane to siliconate in the first gypsum slurry may be fromabout 1:1 to about 1:50, which represents a relatively high amount ofsiliconate as compared to traditional panels. As described herein anddemonstrated by the Examples, it was discovered that relatively lowsiloxane and high siliconate usage, and even siliconate usage with nosiloxane, achieved target water resistant and moisture resistance (e.g.,as measured by 2 hours total immersion and surface water absorptionstandards) without impaired board quality and processing.

In certain embodiments, the ratio of siloxane to siliconate in the firstgypsum slurry is from about 1:1 to about 1:30, such as from about 1:1 toabout 1:20, such as from about 1:1 to about 1:15, such as from about 1:1to about 1:10, such as from about 1:1 to about 1:5. For example, thesiliconate may be present in the first gypsum slurry in an amount offrom about 3 lb/msf to about 50 lb/msf, for a gypsum panel having athickness of about ¼ inch to about 1 inch. For example, the siliconatemay be present in the first gypsum slurry in an amount of from about 10lb/msf to about 40 lb/msf, for a gypsum panel having a thickness ofabout ¼ inch to about 1 inch, such as in an in an amount of from about10 lb/msf to about 30 lb/msf, such as in an amount of from about 15lb/msf to about 30 lb/msf. For example, the siloxane may be present inthe first gypsum slurry in an amount of from about 1 lb/msf to about 20lb/msf, for a gypsum panel having a thickness of about ¼ inch to about 1inch, such as in an amount of from about 2 lb/msf to about 10 lb/msf,for a gypsum panel having a thickness of about ¼ inch to about 1 inch.

The siloxane and siliconate materials may be any suitable siliconate orsiloxane chemistries. For example, the siliconate may be an alkalinemetal alkylsiliconate or an aromaticsiliconate, including but notlimited to, sodium or potassium methylsiliconate, sodium or potassiumethyl siliconate, propylsiliconate, isopropylsiliconate,butylsiliconate, octylsiliconate, phenylsiliconate, or any combinationthereof. For example, the siloxane may be polymethylhydrogensiloxane.

For example, the phosphate salt or polymer may be sodiumtrimetaphosphate (STMP), sodium hexametaphosphate (SHMP), ammoniumpolyphosphate (APP), polyvinyl alcohol (PVA), a hydrophobic latex, or adispersible polymer powder comprising a styrene/maleic acid copolymer, astyrene-butadiene copolymer, a styrene-acrylate, an acrylate, or aterpolymer of ethylene, vinyl chloride and vinyl laurate. Other suitablephosphate salts or polymers such as other hydrophobic latex materialsmay also be used. For example, other suitable phosphate salts mayinclude other metaphosphate, polyphosphate, and pyrophosphate salts,such as ammonium trimetaphosphate, potassium trimetaphosphate, lithiumtrimetaphosphate, calcium trimetaphosphate, sodium calciumtrimetaphosphate, aluminum trimetaphosphate; ammonium, lithium, orpotassium hexametaphosphates; sodium tripolyphosphate, potassiumtripolyphosphate, sodium and potassium tripolyphosphate; calciumpyrophosphate, tetrapotassium pyrophosphate, and/or tetrasodiumpyrophosphate.

In certain embodiments, the phosphate salt or polymer is present in thefirst gypsum slurry in an amount of 0.5 lb/msf to about 50 lb/msf, for agypsum panel having a thickness of about ¼ inch to about 1 inch. Forexample, the phosphate salt or polymer may be present in the firstgypsum slurry in an amount of from about 10 lb/msf to about 30 lb/msf,for a gypsum panel having a thickness of about ¼ inch to about 1 inch.

In some embodiments, the phosphate salt or polymer contains PVA and ispresent in the first gypsum slurry in an amount of from about 10 lb/msfto about 30 lb/msf, for a gypsum panel having a thickness of about ¼inch to about 1 inch. In some embodiments, the phosphate salt or polymeris a phosphate salt, such as sodium trimetaphosphate (STMP), sodiumhexametaphosphate (SHMP), and/or ammonium polyphosphate (APP), and ispresent in the first gypsum slurry in an amount of from about 0.5 lb/msfto about 10 lb/msf, for a gypsum panel having a thickness of about ¼inch to about 1 inch. In some embodiments, the phosphate salt or polymercontains a hydrophobic latex or dispersible polymer powder, such as astyrene/maleic acid copolymer, a styrene-butadiene copolymer, astyrene-acrylate, an acrylate, or a terpolymer of ethylene, vinylchloride and vinyl laurate, and is present in the first gypsum slurry inan amount of from about 3 lb/msf to about 10 lb/msf, for a gypsum panelhaving a thickness of about ¼ inch to about 1 inch.

In certain embodiments, the gypsum core includes multiple layers thatare sequentially applied to a facing material, and allowed to set eithersequentially or simultaneously, as shown in FIG. 1 . In suchembodiments, the first gypsum slurry may form any one or more of theselayers.

In other embodiments, the gypsum core includes a single layer formed bythe first gypsum slurry. In some embodiments, a second facing materialmay be deposited onto a surface of the final gypsum slurry layer (or thesole gypsum slurry layer), to form a dual mat-faced gypsum panel, asshown in FIG. 2 . In certain embodiments, the first gypsum slurry (oreach of the outermost gypsum slurry layers) is deposited in an amount offrom about 5 percent to about 20 percent, by weight, of the gypsum core.The gypsum slurry or multiple layers thereof may be deposited on thefacer material by any suitable means, such as roll coating.

In certain embodiments, the first gypsum slurry (or other gypsum slurrylayers that form the core) contains one or more additional agents toenhance its performance, such as, but not limited to, wetting agents,fillers, accelerators, set retarders, foaming agents, and dispersingagents. Various example uses of such additives will now be described.

In certain embodiments, a wetting agent is selected from a groupconsisting of surfactants, superplasticisers, dispersants, agentscontaining surfactants, agents containing superplasticisers, agentscontaining dispersants, and combinations thereof. For example, thegypsum slurry or layer(s) may include wax, wax emulsions andco-emulsions, silicone, siloxane, or a combination thereof. For example,suitable superplasticisers include Melflux 2651 F and 4930F,commercially available from BASF Corporation. In certain embodiments,the wetting agent is a surfactant having a boiling point of 200° C. orlower. In some embodiments, the surfactant has a boiling point of 150°C. or lower. In some embodiments, the surfactant has a boiling point of110° C. or lower. For example, the surfactant may be a multifunctionalagent based on acetylenic chemistry or an ethoxylated low-foam agent.

In certain embodiments, a surfactant is present in the relevant gypsumslurry in an amount of about 0.01 percent to about 1 percent, by weight.In certain embodiments, the surfactant is present in the relevant gypsumslurry in an amount of about 0.01 percent to about 0.5 percent, byweight. In some embodiments, the surfactant is present in the relevantgypsum slurry in an amount of about 0.05 percent to about 0.2 percent,by weight.

Suitable surfactants and other wetting agents may be selected fromnon-ionic, anionic, cationic, or zwitterionic compounds, such as alkylsulfates, ammonium lauryl sulfate, sodium lauryl sulfate, alkyl-ethersulfates, sodium laureth sulfate, sodium myreth sulfate, docusates,dioctyl sodium sulfosuccinate, perfluorooctanesulfonate,perfluorobutanesulfonate, linear alkylbenzene sulfonates, alkyl-arylether phosphates, alkyl ether phosphate, alkyl carboxylates, sodiumstearate, sodium lauroyl sarcosinate, carboxylate-basedfluorosurfactants, perfluorononanoate, perfluorooctanoate, amines,octenidine dihydrochloride, alkyltrimethylammonium salts, cetyltrimethylammonium bromide, cetyl trimethylammonium chloride,cetylpyridinium chloride, benzalkonium chloride, benzethonium chloride,5-Bromo-5-nitro-1,3-dioxane, dimethyldioctadecylammonium chloride,cetrimonium bromide, dioctadecyldimethylammonium bromide, sultaines,cocamidopropyl hydroxysultaine, betaines, cocamidopropyl betaine,phospholipids phosphatidylserine, phosphatidylethanolamine,phosphatidylcholine, sphingomyelins, fatty alcohols, cetyl alcohol,stearyl alcohol, cetostearyl alcohol, stearyl alcohols. oleyl alcohol,polyoxyethylene glycol alkyl ethers, octaethylene glycol monododecylether, pentaethylene glycol monododecyl ether, polyoxypropylene glycolalkyl ethers, glucoside alkyl ethers, polyoxyethylene glycol octylphenolethers, polyoxyethylene glycol alkylphenol ethers, glycerol alkylesters, polyoxyethylene glycol sorbitan alkyl esters, sorbitan alkylesters, cocamide MEA, cocamide DEA, dodecyldimethylamine oxide,polyethoxylated tallow amine, and block copolymers of polyethyleneglycol and polypropylene glycol. For example, suitable surfactantsinclude Surfynol 61, commercially available from Air Products andChemicals, Inc. (Allentown, Pa.).

In certain embodiments, the gypsum slurry (or one or more layersthereof) is substantially free of foam, honeycomb, excess water, andmicelle formations. As used herein, the term “substantially free” refersto the slurry containing lower than an amount of these materials thatwould materially affect the performance of the panel. That is, thesematerials are not present in the slurry in an amount that would resultin the formation of pathways for liquid water in the glass mat of a setpanel, when under pressure.

In certain embodiments, the panel core slurry (or layers thereof) may bedeposited on a horizontally oriented moving web of facer material, suchas pre-coated fibrous mat or paper facing material. A second coated oruncoated mat may be deposited onto the surface of the panel core slurryopposite the mat, e.g., a non-coated surface of the second mat contactsthe panel core slurry. In some embodiments, a moving web of a mat may beplaced on the upper free surface of the aqueous panel core slurry. Thus,the panel core material may be sandwiched between two facer mats, one orboth having a mat coating. In certain embodiments, allowing the panelcore material and/or mat coating to set includes curing, drying, such asin an oven or by another suitable drying mechanism, or allowing thematerial(s) to set at room temperature (i.e., to self-harden).

A barrier coating may be applied to one or both (in embodiments havingtwo) mat surfaces, prior to or after drying of the mat. In someembodiments, the mats are pre-coated when they are associated with thepanel core slurry. In some embodiments, depositing a barrier coatingonto the second surface of the first coated mat occurs after setting thefirst gypsum slurry to form at least a portion of a gypsum core. In someembodiments, the gypsum core coated with the barrier coating is cured,dried, such as in an oven or by another suitable drying mechanism, orthe materials are allowed to set at room temperature. In someembodiment, infrared heating is used to flash off water and dry thebarrier coating.

Methods of constructing a building sheathing system, as shown in FIG. 3, are also provided herein, including installing at least two gypsumpanels 300 having an interface therebetween, and applying a seamingcomponent 320 at the interface between the at least two of the gypsumpanels 300. Gypsum panels used in these methods may have any of thefeatures, properties, or combinations of features and/or properties,described herein. Sheathing systems constructed by these methods mayhave any of the features, properties, or combinations or features and/orproperties, described herein. The seaming component may be any suitableseaming component as described herein.

Panels and Systems

Gypsum panels having improved water absorption resistance may be made byany of the methods described herein. Such panels may beneficiallydisplay one or more of the following water absorption resistancecharacteristics: an average water absorption of not more than 15 percentby weight, after 2 hours of immersion, according to ASTMC1396/C1396M-14a (2014), an average water absorption of not more than 5percent by weight, after 2 hours of immersion, according to ASTMC1396/C1396M-14a (2014), an average water absorption of not more than 15percent by weight, after 2 hours of immersion, according to ASTMC1177/C117M-13 (2013), and/or an average water absorption of not morethan 5 percent by weight, after 2 hours of immersion, according to ASTMC1178/C1188M-13 (2013).

In certain embodiments, as shown in FIG. 1 , a gypsum panel 100 includesa gypsum core 101 having a first surface and a second opposed surface,and a first facer material 104 (shown here as a fibrous mat, thoughpaper facing materials may also be used, as discussed herein) associatedwith the first surface of the gypsum core 101, such that gypsum of thegypsum core penetrates at least a portion of the first mat 104. Thevarious layers are illustrated as separate layers in the figures forease of illustration; however, it should be understood that overlap ofthese materials may occur at their interfaces.

In certain embodiments, the gypsum panel 100 includes a set gypsum core101 associated with a first surface of first fibrous mat 104 and anoptional mat coating 106 applied to a second surface of the firstfibrous mat 104. For example, the mat coating may have a dry weight offrom about 1 pound to about 25 pounds per thousand square feet (lb/msf)of board surface, such as less than 15 pounds per thousand square feet.For example, the mat coating may be substantially continuous, such thatit covers at least 99 percent of the board surface, or at least 99.9percent of the mat surface.

Suitable coating materials (i.e., the precursor to the dried matcoating) contain at least one suitable polymer binder. Suitable polymerbinders may be selected from polymeric emulsions and resins, e.g.acrylics, siloxane, silicone, styrene-butadiene copolymers,polyethylene-vinyl acetate, polyvinyl alcohol, polyvinyl chloride (PVC),polyurethane, urea-formaldehyde resin, phenolics resin, polyvinylbutyryl, styrene-acrylic copolymers, styrene-vinyl-acrylic copolymers,styrene-maleic anhydride copolymers. In some embodiments, the polymerbinder is an acrylic latex or a polystyrene latex. In some embodiments,the polymer binder is hydrophobic. In certain embodiments, the binderincludes UV curable monomers and/or polymers (e.g. epoxy acrylate,urethane acrylate, polyester acrylate). In certain embodiments, the matcoating contains the polymer binder in an amount of from about 5 percentto about 75 percent, by weight, on a dry basis.

Examples of suitable polymer binders that may be used in the continuousbarrier coatings described herein include SNAP 720, commerciallyavailable from Arkema Coating Resins, which is a structurednano-particle acrylic polymer containing 100% acrylic latex and 49%solids by weight, with a 0.08 micron particle size; SNAP 728,commercially available from Arkema Coating Resins, which is a structurednano-acrylic polymer containing 100% acrylic latex and 49% solids byweight, with a 0.1 micron particle size; and NEOCAR 820, commerciallyavailable from Arkema Coating Reins, which is a hydrophobic modifiedacrylic latex containing 45% solids by weight, with a 0.07 micronparticle size.

In certain embodiments, the mat coating also contains one or moreinorganic fillers. For example, the inorganic filler may be calciumcarbonate or another suitable filler known in the industry. In certainembodiments, the filler is an inorganic mineral filler, such as groundlimestone (calcium carbonate), clay, mica, gypsum (calcium sulfatedihydrate), aluminum trihydrate (ATH), antimony oxide, sodium-potassiumalumina silicates, pyrophyllite, microcrystalline silica, and talc(magnesium silicate). In certain embodiments, the filler may inherentlycontain a naturally occurring inorganic adhesive binder. For example,the filler may be limestone containing quicklime (CaO), clay containingcalcium silicate, sand containing calcium silicate, aluminum trihydratecontaining aluminum hydroxide, cementitious fly ash, or magnesium oxidecontaining either the sulfate or chloride of magnesium, or both. Incertain embodiments, the filler may include an inorganic adhesive binderas a constituent, cure by hydration, and act as a flame suppressant. Forexample, the filler may be aluminum trihydrate (ATH), calcium sulfate(gypsum), and the oxychloride and oxysulfate of magnesium. For example,fillers may include MINEX 7, commercially available from the CaryCompany (Addison, Ill.); IMSIL A-10, commercially available from theCary Company; and TALCRON MP 44-26, commercially available fromSpecialty Minerals Inc. (Dillon, Mont.). The filler may be in aparticulate form. For example, the filler may have a particle size suchthat at least 95% of the particles pass through a 100 mesh wire screen.

In certain embodiments, the precursor material that forms the matcoating also contains water. For example, the coating material maycontain the polymer binder in an amount of from about 35 percent toabout 80 percent, by weight, and water in an amount of from about 20percent to about 30 percent, by weight. In embodiments containing thefiller, the continuous barrier coating material may also contain aninorganic filler in an amount of from about 35 percent to about 80percent, by weight. In some embodiments, the polymer binder and theinorganic filler are present in amounts of within 5 percent, by weight,of each other. For example, the polymer binder and filler may be presentin a ratio of approximately 1:1.

In some embodiments, the mat coating also includes water and/or otheroptional ingredients such as colorants (e.g., dyes or pigments),transfer agents, thickeners or rheological control agents, surfactants,ammonia compositions, defoamers, dispersants, biocides, UV absorbers,and preservatives. Thickeners may include hydroxyethyl cellulose;hydrophobically modified ethylene oxide urethane; processed attapulgite,a hydrated magnesium aluminosilicate; and other thickeners known tothose of ordinary skill in the art. For example, thickeners may includeCELLOSIZE QP-09-L and ACRYSOL RM-2020NPR, commercially available fromDow Chemical Company (Philadelphia, Pa.); and ATTAGEL 50, commerciallyavailable from BASF Corporation (Florham Park, N.J.). Surfactants mayinclude sodium polyacrylate dispersants, ethoxylated nonionic compounds,and other surfactants known to those of ordinary skill in the art. Forexample, surfactants may include HYDROPALAT 44, commercially availablefrom BASF Corporation; and DYNOL 607, commercially available from AirProducts (Allentown, Pa.). Defoamers may include multi-hydrophobe blenddefoamers and other defoamers known to those of ordinary skill in theart. For example, defoamers may include FOAMASTER SA-3, commerciallyavailable from BASF Corporation. Ammonia compositions may includeammonium hydroxide, for example, AQUA AMMONIA 26 BE, commerciallyavailable from Tanner Industries, Inc. (Southampton, Pa.). Biocides mayinclude broad-spectrum microbicides that prohibit bacteria and fungigrowth, antimicrobials such as those based on the activediiodomethyl-ptolylsulfone, and other compounds known to those ofordinary skill in the art. For example, biocides may include KATHON LX1.5%, commercially available from Dow Chemical Company, POLYPHASE 663,commercially available from Troy Corporation (Newark, N.J.), and AMICALFlowable, commercially available from Dow Chemical Company. Biocides mayalso act as preservatives. UV absorbers may include encapsulatedhydroxyphenyl-triazine compositions and other compounds known to thoseof ordinary skill in the art, for example, TINUVIN 477DW, commerciallyavailable from BASF Corporation. Transfer agents such as polyvinylalcohol (PVA) and other compounds known to those of ordinary skill inthe art may also be included in the coating composition.

In some embodiments, as shown in FIG. 1 , the gypsum of the gypsum core101 penetrates a remaining portion of the first fibrous mat 104 suchthat voids in the mat 104 are substantially eliminated and the waterresistance of the panel 100 is further enhanced. For example, in oneembodiment, the first mat 104 has a mat coating 106 on a surfaceopposite the gypsum core 101, the mat coating 106 penetrating a portionof the first mat 104, to define the remaining portion of the first mat104. That is, gypsum of the gypsum core 101 may penetrate a remainingfibrous portion of the first fibrous mat 104 such that voids in thefirst mat 104 are substantially eliminated.

As used herein the phrase “such that voids in the mat are substantiallyeliminated” and similar phrases, refer to the gypsum slurry, and thusthe set gypsum, of the gypsum core filling all or nearly all of theinterstitial volume of the fibrous mat that is not filled by the coatingmaterial. In certain embodiments, the gypsum of the gypsum core fills atleast 95 percent of the available interstitial volume of the mat. Insome embodiments, the gypsum core fills at least 98 percent of theavailable interstitial volume of the mat. In further embodiments, thegypsum core fills at least 99 percent of the available interstitialvolume of the mat.

By maximizing gypsum slurry penetration into the side of the matreceiving gypsum, the movement of water under the mat coating within theglass mat of the finished panel when exposed to bulk water headpressures may be substantially and adequately reduced, withoutsignificantly altering the water vapor transmission rate (i.e., theability to dry) of the finished panel. Thus, the gypsum panels disclosedherein may further display one or more improved water-resistive barrierproperties.

In certain embodiments, the mat 104 is a nonwoven fiberglass mat. Forexample, the glass fibers may have an average diameter of from about 10to about 17 microns and an average length of from about ¼ inch to about1 inch. For example, the glass fibers may have an average diameter of 13microns (i.e., K fibers) and an average length of ¾ inch. In certainembodiments, the nonwoven fiberglass mats have a basis weight of fromabout 1.5 pounds to about 3.5 pounds per 100 square feet of the mat. Themats may each have a thickness of from about 20 mils to about 35 mils.The fibers may be bonded together to form a unitary mat structure by asuitable adhesive. For example, the adhesive may be a urea-formaldehyderesin adhesive, optionally modified with a thermoplastic extender orcross-linker, such as an acrylic cross-linker, or an acrylate adhesiveresin.

In certain embodiments, as shown in FIG. 1 , the gypsum core 101includes two or more gypsum layers 102, 108. For example, the gypsumcore may include various gypsum layers having different compositions. Insome embodiments, the first gypsum layer 102 that is in contact with themat 104 (i.e., the layer that forms an interface with the coatingmaterial 106 and at least partially penetrates the first mat) is a slatecoat layer. In some embodiments, the first gypsum layer 102 is presentin an amount from about 5 percent to about 20 percent, by weight, of thegypsum core 101. In certain embodiments, the slate coat layer is formedfrom the first gypsum slurry described herein (i.e., the slurry havingthe high siliconate content, with or without siloxane). In otherembodiments, the entire panel core is formed from the first gypsumslurry. The first gypsum slurry (i.e., the slurry containing arelatively high amount of siliconate, with or without a relatively lowamount of siloxane) may form one or more of these layers.

In certain embodiments, as shown in FIG. 2 , a gypsum panel 200 includestwo fibrous mats 204, 212 (which could alternatively be paper facers)that are associated with the gypsum core 201. The second mat 212 ispresent on a face of the gypsum core 201 opposite the first mat 204. Insome embodiments, only the first mat 204 has a mat coating 206 on asurface thereof. In other embodiments, both mats 204, 212 have a coating206, 214 on a surface thereof opposite the gypsum core 201. In someembodiments, the gypsum core 201 includes three gypsum layers 202, 208,210. One or both of the gypsum layers 202, 210 that are in contact withthe mats 204, 212 may be a slate coat layer. In certain embodiments, oneor both of the gypsum layers 202, 210 that are in contact with the mats204, 212 may be a slate coat layer with hydrophobic characteristicsand/or a wet density of from about 88 pcf to about 98 pcf, or of fromabout 93 pcf to about 96 pcf.

The layers of the gypsum core may generally be similar to gypsum coresused in other gypsum products, such as gypsum wallboard, dry wall,gypsum board, gypsum lath, and gypsum sheathing. For example, the gypsumcore may be formed by mixing water with powdered anhydrous calciumsulfate or calcium sulfate hemihydrate, also known as calcined gypsum orstucco, to form the aqueous gypsum slurry, and thereafter allowing theslurry mixture to hydrate or set into calcium sulfate dihydrate, arelatively hard material. In certain embodiments, the gypsum coreincludes about 80 weight percent or above of set gypsum (i.e., fullyhydrated calcium sulfate). For example, the gypsum core may includeabout 85 weight percent set gypsum. In some embodiments, the gypsum coreincludes about 95 weight percent set gypsum. The gypsum core may alsoinclude a variety of additives, such as accelerators, set retarders,foaming agents, and dispersing agents, in addition to thesiliconate/siloxane, as discussed herein.

In certain embodiments, one or more layers of the gypsum core alsoincludes reinforcing fibers, such as chopped glass fibers. For example,the gypsum core, or any layer(s) thereof, may include up to about 0.6pounds of reinforcing fibers per 100 square feet of panel. For example,the gypsum core, or a layer thereof, may include about 0.3 pounds ofreinforcing fibers per 100 square feet of panel. The reinforcing fibersmay have a diameter between about 10 and about 17 microns and have alength between about 6.35 and about 12.7 millimeters.

The gypsum core, or one or more layers thereof, may also include one ormore additives that enhance the inherent fire resistance of the gypsumcore. Such additives may include chopped glass fibers, other inorganicfibers, vermiculite, clay, Portland cement, and other silicates, amongothers.

In certain embodiments, as discussed above, the building panelsdescribed herein may display one or more improved performancecharacteristics such as water repellence, moisture migration, and otherweather-related properties.

Building sheathing systems are also provided herein, and include atleast two of the improved water-resistive gypsum panels describedherein, including any features, or combinations of features, of thepanels described herein.

In certain embodiments, as shown in FIG. 3 , a building sheathing systemincludes at least two gypsum panels 300 and a seaming component 320configured to provide a seam at an interface between at least two of thegypsum panels 300. In certain embodiments, the seaming componentcomprises tape or a bonding material. For example, the seaming componentmay be a tape including solvent acrylic adhesives, a tape having apolyethylene top layer with butyl rubber adhesive, a tape having analuminum foil top layer with butyl rubber adhesive, a tape having anEPDM top layer with butyl rubber adhesive, a tape having a polyethylenetop layer with rubberized asphalt adhesive, or a tape having an aluminumfoil top layer with rubberized asphalt adhesive or rubberized asphaltadhesives modified with styrene butadiene styrene. For example, theseaming component may be a bonding material containing silyl terminatedpolyether, silyl modified polymers, silicones, synthetic stucco plastersand/or cement plasters, synthetic acrylics, sand filled acrylics, and/orjoint sealing chemistries comprising solvent based acrylics, solventbased butyls, latex (water-based, including EVA, acrylic), polysulfidespolyurethanes, and latexes (water-based, including EVA, acrylic).

Thus, the above-described enhanced panels may be installed with either atape, liquid polymer, or other suitable material, to effectively treatareas of potential water and air intrusion, such as seams, door/windowopenings, penetrations, roof/wall interfaces, and wall/foundationinterfaces. As such, the building sheathing panels, when used incombination with a suitable seaming component, create an effectivewater-resistive barrier envelope.

EXAMPLES

Embodiments of the water-resistive panels disclosed herein wereconstructed and tested, as described below.

First, sample gypsum panels were made using various amounts and ratiosof siloxane, siliconate, and phosphate salts and polymers in the gypsumcore slurry. Specifically, the gypsum core slurry was made by combiningstucco, water, in consistent amounts, with varying amounts ofsiliconate, with or without siloxane (at various siloxane:siliconateratios), and various phosphate salts or polymers, according to thesample parameters shown below in Tables 1-4. A 2-hour water absorptiontest was performed in which the sample panels were immersed for 2 hoursand then the percent weight gain was measured. Comparative samplescontaining no siloxane, siliconate, and/or phosphate salts or polymerswere also tested. The results are shown in Tables 1-4 and the waterabsorption test results are shown in FIGS. 4-7 .

Table 1 relates to experimental gypsum panels made with 1600 lbs/msfgypsum stucco, siliconate, and polyvinyl alcohol (PVA), in varyingamounts. The results of the water absorption tests are also given, andare illustrated in FIG. 4 . As can be seen, a panel containing PVA andsiliconate in amounts of 10 lbs/msf and 15 lbs/msf, respectively, had awater absorption of 3.63%. By comparison, sample panels having the sameamount of siliconate, without PVA, had a water absorption of 37.38%,while sample panels having the same amount of PVA, without siliconate,had a water absorption of 62.48%. Such a significant synergistic effectbetween these amounts of PVA and siliconate was not predictable. Infact, each sample containing PVA and siliconate displayed at least abouta 15% lower weight percent gain then identical panels without the PVA.

Thus, it was surprisingly determined that gypsum boards that containabout 10 lbs/msf PVA and about 15 lbs/msf siliconate are ten times morewater resistant than boards with solely 15 lbs/msf siliconate (3.63%compared to 37.38%). PVA/Siliconate blended ratios ranging from about1.0/1.0 to about 1.0/10.0, by weight, were found to providewater-resistant performance in gypsum boards. The addition rate for PVAand siliconate in such compositions may range from about 3.0 to about50.0 lbs/msf and about 5.0 to about 50.0 lbs/msf, respectively, such asaddition rates for each component being about 10.0 to about 30.0lbs/msf.

TABLE 1 Sample Board Parameters and Test Results Components ControlSiliconate PVA PVA PVA PVA PVA (lbs/msf) 0 0 10 5 8 10 Siliconate(lbs/msf) 0 15 0 15 15 15 Stucco (lbs/msf) 1600 1600 1600 1600 1600 1600Water:Stucco Ratio 0.78 0.96 1.07 1.07 1.07 1.07 % Water Absorption (By60.36 37.38 62.48 20.71 15.82 3.63 Weight)

Table 2 relates to experimental gypsum panels made with 1600 lbs/msfstucco, a water:stucco ratio of 0.96, siliconate, and sodiumtrimetaphosphate (STMP), in varying amounts. Table 3 relates toexperimental gypsum panels made with 1600 lbs/msf stucco, a water:stuccoratio of 0.96, siliconate and siloxane, in varying ratios, and sodiumtrimetaphosphate (STMP), in varying amounts. The tables and FIGS. 5 and6 illustrate the results of the 2-hour absorption tests.

As can be seen at Table 2 and FIG. 5 , a panel containing STMP andsiliconate in amounts of 2 lbs/msf and 25 lbs/msf, respectively, had awater absorption of 9.48%. By comparison, sample panels having the sameamount of siliconate, without STMP, had a water absorption of 19.53%,while sample panels having the same amount of STMP, without siliconate,had a water absorption of 55.84%. Such a significant synergistic effectbetween these amounts of STMP and siliconate was not predictable. Infact, each sample containing STMP and siliconate displayed at leastabout a 10% lower weight percent gain then identical panels without theSTMP.

As can be seen at Table 3 and FIG. 6 , a panel containing STMP andsiloxane/siliconate in amounts of 2 lbs/msf and 5/10 lbs/msf,respectively, had a water absorption of 1.19%. By comparison, samplepanels having the same amount of siloxane/siliconate, without STMP, hada water absorption of 15.24%. Such a significant synergistic effectbetween these amounts of STMP and siloxane/siliconate was notpredictable. Moreover, the use of relatively low siloxane/highsiliconate ratios is opposite the traditional relative blended amountsof these components. In particular, blends of high siloxane/lowsiliconate ratios of up to 10/1, by weight, are more traditionallyutilized to achieve water-resistant requirements. In contrast, theembodiments of the present disclosure containing siloxane and siliconatemay contain these components in a reverse ratio, i.e.,siloxane/siliconate from about 1.0/1.0 to 1.0/30.0, such as from about1.0/1.0 to 1.0/10.0.

Thus, it was surprisingly found that gypsum boards containing a 2/10lbs/msf blend of siloxane/siliconate with 2.0 lbs/msf STMP, displayedimproved water resistance that was approximately 15 times more thansolely 2/10 lbs/msf siloxane/siliconate blend (2.17% vs. 31.49%). TheSTMP addition rate may be from 0.5 to 20.0 lb/msf, such as ranging fromabout 0.5 to 10.0 lb/msf. The siliconate addition rate range may be fromabout 5.0 to 50.0 lb/msf, such as from about 10.0 to 301b/msf, and thesiloxane addition rate range can be from about 1.0 to 20.0 lb/msf, suchas from about 2.0 to 10.0 lb/msf.

TABLE 2 Sample Board Parameters and Test Results Siliconate lbs/msf 0.0015.00 25.00 0.00 lbs/msf STMP 56.20 37.38 19.53 0.50 lbs/msf STMP 55.3029.72 16.44 1.00 lbs/msf STMP 53.91 23.68 11.45 2.00 lbs/msf STMP 55.8417.43 9.48

TABLE 3 Sample Board Parameters and Test Results Siloxane/Siliconate,lbs/msf 2/10# 2/15# 5/10# 5/20# 0.00 lbs/msf STMP 31.49 21.2 15.24 6.080.50 lbs/msf STMP 17.06 14.42 8.34 2.29 1.00 lbs/msf STMP 16.77 10.512.29 1.53 2.00 lbs/msf STMP 2.17 3.06 1.19 0.71

Table 4 relates to experimental gypsum panels made with 1600 lbs/msfgypsum stucco, siliconate, and various hydrophobic latex copolymers andterpolymers, in varying amounts. The results of the water absorptiontests are also given, and are illustrated in FIG. 7 . Generally,hydrophobic latexes and dispersible polymer powders, e.g. styrene/maleicacid copolymer (such as NovaCote1936HS, commercially available from G-PResins), styrene-butadiene copolymer (such as Genceal 8100, commerciallyavailable from Omnova), terpolymer of ethylene, vinyl chloride and vinyllaurate (such as Vinnaps 8034, commercially available from Wacker), donot provide good water-resistant benefits to gypsum boards. However,these experiments surprisingly showed that gypsum boards containing 5lbs/msf latex with 15 lbs/msf siliconate displayed an improved waterresistance nearly twice as much as boards solely with 15 lbs/msfsiliconate. The addition rate for latex may range from about 1 to 20.0lb/msf, such as from about 3 to 10.0 lbs/msf. The siliconate additionrate range may be from about 5.0 to 50.0 lbs/msf, such as from about10.0 to 30 lbs/msf.

TABLE 4 Sample Board Parameters and Test Results Terpolymer of Styrene-ethylene, vinyl Styrene/maleic butadiene chloride and Component ControlSiliconate acid copolymer copolymer vinyl laurate Hydrophobic 0 0 150 35 150 3 5 30 3 5 Latex (lbs/msf) Siliconate 0 15 0 15 15 0 15 15 0 15 15(lbs/msf) Latex: 0 0.53 0.4 0.24 0.13 0 0 0 0 1.88 1.88 SiliconateStucco 1600 1600 1600 1600 1600 1600 1600 1600 1600 1600 1600 (lbs/msf)Water: 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96 Stucco2-hr Water 06.40 37.40 61.10 30.10 14.90 59.20 35.10 23.00 51.40 33.0019.80 absorption (%)

Table 5 relates to experimental gypsum panels made using stucco, varyingamounts and combinations of siloxane and siliconate and various amountsof three phosphate salts (sodium trimetaphosphate (STMP), sodiumhexametaphosphate (SHMP), and ammonium polyphosphate (APP)). The resultsof water absorption tests are also given, and are illustrated in FIG. 8. As can be seen, addition of 2 lbs/msf of each of the tested phosphatesalts resulted in significant improvements in water resistance of theresulting gypsum panels, as compared to otherwise identical panels notcontaining the phosphate salt.

TABLE 5 Sample Board Parameters and Test Results 2/10# 2/15# Siloxane/Siloxane/ 15# Stucco + Siliconate + Siliconate + Siliconate + PhosphatePhosphate Phosphate Phosphate Salt Salt Salt Salt 2# STMP 55.8% 2.17%3.06% 17.4% 2# SHMP 53.3%  7.9%  6.2% 10.7% 2# APP 49.2% 17.6% 12.1%21.4% Siloxane/ 34.8% 18.8% 42.8% Siliconate Only

In sum, these experiments demonstrated that the addition of phosphatesalts and polymers in the gypsum core slurry, at sufficient levels, cansignificantly enhance the water resistance performance of siliconate,and/or low siloxane/high siliconate blends. A synergisticwater-resistant improvement effect was observed when either a phosphatesalt and/or polymer was mixed with either siliconate, or a lowsiloxane/high siliconate blend, in comparison to their solecounterparts, siliconate and low siloxane/high siliconate blends. Thusit was surprisingly found that phosphate salts and polymers, such assodium trimetaphosphate (STMP), sodium hexametaphosphate (SHMP),ammonium polyphosphate (APP), polyvinyl alcohol (PVA), a hydrophobiclatex, or a dispersible polymer powder comprising a styrene/maleic acidcopolymer, a styrene-butadiene copolymer, a styrene-acrylate, anacrylate, or a terpolymer of ethylene, vinyl chloride and vinyl lauratecan significantly enhance water resistance performance of siliconate,and/or low siloxane/high siliconate blends, in comparison to neatsiliconate and neat low siloxane/high siliconate blends.

While the disclosure has been described with reference to a number ofembodiments, it will be understood by those skilled in the art that theinvention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions, or equivalent arrangements not describedherein, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

We claim:
 1. A method of making a gypsum panel, comprising: forming afirst gypsum slurry by combining stucco, water, a siliconate, siloxane,and at least one of a phosphate salt or a polymer; and setting the firstgypsum slurry to form at least part of a core of the gypsum panel,wherein: the siliconate is present in the first gypsum slurry in anamount of 25 lb/msf to 50 lb/msf, and a ratio of the siloxane to thesiliconate in the first gypsum slurry is from 1:10 to 1:30.
 2. Themethod of claim 1, wherein the phosphate salt or polymer comprisessodium trimetaphosphate (STMP), sodium hexametaphosphate (SHMP),ammonium polyphosphate (APP), polyvinyl alcohol (PVA), a hydrophobiclatex, or a dispersible polymer powder comprising a styrene/maleic acidcopolymer, a styrene-butadiene copolymer, a styrene-acrylate, anacrylate, or a terpolymer of ethylene, vinyl chloride and vinyl laurate.3. The method of claim 1, wherein the siliconate is present in the firstgypsum slurry in an amount of 25 lb/msf to 40 lb/msf, and a thickness ofthe gypsum panel is ¼ inch to ¾ inch.
 4. The method of claim 1, whereinthe siliconate is present in the first gypsum slurry in an amount offrom 25 lb/msf to 30 lb/msf, and a thickness of the gypsum panel is ¼inch to ¾ inch.
 5. The method of claim 1, wherein a ratio of siloxane tosiliconate in the first gypsum slurry is from 1:15 to 1:20.
 6. Themethod of claim 1, wherein a ratio of siloxane to siliconate in thefirst gypsum slurry is 1:15.
 7. The method of claim 1, wherein thesiloxane is present in the first gypsum slurry in an amount of from 1lb/msf to 5 lb/msf, and a thickness of the gypsum panel is ¼ inch to ¾inch.
 8. The method of claim 1, wherein the siloxane is present in thefirst gypsum slurry in an amount of from 2 lb/msf to 5 lb/msf, and athickness of the gypsum panel is ¼ inch to ¾ inch.
 9. The method ofclaim 1, wherein the gypsum panel displays a 2-hour water absorptiontest weight increase of at least 10 weight percent less than anotherwise identical comparative panel containing no phosphate salt orpolymer in its core,
 10. The method of claim 1, wherein the siliconatecomprises sodium or potassium methylsiliconate, sodium or potassiumethyl siliconate, propylsiliconate, isopropylsiliconate,butylsiliconate, octylsiliconate, phenylsiliconate, or any combinationthereof.
 11. The method of claim 1, wherein the siloxane comprisespolymethylhydrogensiloxane.
 12. The method of claim 1, wherein thephosphate salt or polymer is present in the first gypsum slurry in anamount of 0.5 lb/msf to 50 lb/msf, and a thickness of the gypsum panelis ¼ inch to ¾ inch.
 13. The method of claim 1, wherein the phosphatesalt or polymer is present in the first gypsum slurry in an amount offrom 10 lb/msf to 30 lb/msf, and a thickness of the gypsum panel is ¼inch to ¾ inch.
 14. The method of claim 1, wherein the phosphate salt orpolymer comprises PVA that is present in the first gypsum slurry in anamount of from 10 lb/msf to 30 lb/msf, and a thickness of the gypsumpanel is ¼ inch to ¾ inch.
 15. The method of claim 1, wherein thephosphate salt or polymer comprises STMP, SHMP, or APP, that is presentin the first gypsum slurry in an amount of from 0.5 lb/msf to 10 lb/msf,and a thickness of the gypsum panel is ¼ inch to ¾ inch.
 16. The methodof claim 1, wherein the phosphate salt or polymer comprises ahydrophobic latex that is present in the first gypsum slurry in anamount of from 3 lb/msf to 10 lb/msf, and a thickness of the gypsumpanel is ¼ inch to ¾ inch.
 17. The method of claim 1, wherein the gypsumpanel displays at least one of: an average water absorption of not morethan 15 percent by weight, after 2 hours of immersion, according to ASTMC1396/C1396M-14a (2014), an average water absorption of not more than 15percent by weight, after 2 hours of immersion, according to ASTMC1177/C117M-13 (2013), or an average water absorption of not more than 5percent by weight, after 2 hours of immersion, according to ASTMC1178/C1188M-13 (2013).
 18. The method of claim 1, further comprisingdepositing the first gypsum slurry onto a first surface of a facermaterial.
 19. The method of claim 18, wherein the facer materialcomprises a fiberglass mat or a paper facer.
 20. A gypsum panel made bythe method of claim 1.